US2663399A - Proportional spacing apparatus - Google Patents

Description

Dec. 22, 1953 E. FREY ET AL 2,663,399

PROPORTIONAL SPACING APPARATUS Filed March 15, 1952 2 Sheets-Sheet l /NVEN 70?.9

Dec. 22, 1953 E. FREY ET AL PROPORTIONAL SPACING APPARATUS 2 Sheets-Sheet 2 Filed March 15, 1952 Patentecl Dec. 22, 1953 UNITED STATES PATENT OFFICE 'PROPORTIONAL SPACING APPARATUS Erik-Frey and Russell E. Hattis, Chicago, 111.

Application March 15, 1952, -Serial N o."276,849

Iii-Claims. I

This invention "generally relates to :typewriting machines and, more particularly this invention relates to proportional .spacing apparatus .for use with typewriting machines.

One object of this invention is to provide an improved'spacing apparatus wherein the spacing produced is proportional to thesize of the letter typed.

Another object of the instant invention is to provide a novel proportional spacing apparatus which may be used to .readily convert conventional fixed spacing typewriters to proportional spacing typewriters.

Still another object :of the instant "invention is to provide a novel and improved proportional spacing apparatus which operates through electrical relays to move the carriage of :a typewriter.

A further object of the instant invention is to provide a novel and improved apparatus which provides both proportional front and back spacing for a typewriter.

Another object :of @the :instant invention is to provide a novel and improved variable spacing mechanism which also provides for adjustable line spreading in a typewriter.

A still further object of the instant invention is to provide a novel and simpleswitch mechanism for actuation by the character keys of a proportional spacing typewriter to energize electrical apparatus which controls the movement of the carriage which in turn controls the spacing between the printed letters. 1

Other objects of the instant invention will -become apparent upon making reference to the specification which follows and the drawings wherein:

Figure 1 shows aside view of the apparatus of one embodiment of the instant invention added to a conventional fixed spacing typewriter;

Figure 2 is a rear view of a portion of the apparatus shown in Figure 1;

Figure 3 shows the switch actuating apparatus which is operated directly by the character keys of the typewriter .of Figure 1;

Figure eshows a modificationoi the apparatus of Figure 3;

Figure 5 shows a sample wiring diagram for the operation .of the relay mechanism shown in Figures 1 and 2;

Figure 6 shows a modification of the relay ac tuation mechanism shown in Figures 1 and 2;

:Figure 7 shows an improvement over the relay mechanism shown in Figures 1 and 2;

Figure 8 is a view of a portion ofthe apparatus of Figure 7 in a different operating condition than there shown.

The description that follows will describe several embodiments of the instant invention as applied to the conversion of a conventional fixed spacing typewriter to a proportional spacing typewriter with a minimum of effort and expense. It should be understood however that the invention may be incorporated into a typewriter as manufactured. Also, numerous modifications maybe made of the specific and preferred embodiments of the instant invention without deviating from the broader generic aspects of the instant invention.

In the drawings to be described, the parts of the conventional fixed spaced typewriter to which the invention is applied in the drawings have been omitted for purposes of simplification with only the outline thereof shown in dotted lines. The parts, which must be added to the conventional fixed spacing typewriter to adapt it for proportional spacing, are shown in solid lines. Also, like reference numerals in the several figures represent the same elements.

The conventional fixed spacing typewriter generally includes a rack fixed to the carriage and a pawl which normally engages the rack. The

force for moving the carriage is generally provided by a spring which is placed under tension when the carriage is manually moved to its starting position. The pawl engages the rack "until a character or spacing key is struck. Then the pawl is released from engagement with the rack momentarily which allows the carriage to move under the force of the spring at a fixed amount which is independent of the size of the letter struck. Such a typewriter also includes a lever which frees the rack of the carriage from engagement with the pawl above mentioned. Then the carriage may be freely translated by hand. Such a lever will be hereinafter referred 'to as the carriage release lever.

Since all of these above elements are conventional and well known, the detailed description thereof has been-omitted.

The present invention makes it possible to simply convert a fixed spacing typewriter to a proportional spacing typewriter which spaces the letters of a word an amount proportional to the size of the letters of the word. Thus, for example, when the character hey printing the letter 1' is struck, the carriage will be moved, say, one unit; while when the character key printing the letter w is struck, the carriage will be moved, six units. Such a carriage action saves paper as well as providing printed matter having a much more desirable appearance.

Thereare numerous proportional spacing typewriters in the prior art, but none have the simplicity of the instant invention which makes it possible to readily convert fixed spacing typewriters to proportional spacing typewriters. Also, the existing proportional spacing typewriters do not provide for automatic proportional back spacing or have adjustable line spreading features which are as simple and eifective as the line spreading mechanism which is to be hereinafter described.

One feature of the instant invention comprises mounting a rotatable feed screw on the frame portion of a fixed spacing typewriter and con-. necting an arm to the carriage which rides in the groove of the thread of the feed screw. A ratchet gear mechanism is connected to the end of the feed screw and is used to impart rotary motion to the screw. The ratchet mechanism is operated by an electromagnetic device which moves the ratchet mechanism an amount pro portional to the energized condition of the electromagnet. The energization of the electromagnet is controlled by sets of electrical contacts which are actuated by the keys of the typewriter. The electromagnet may include a plurality of separate windings which when separately energized impart a different amount of motion to the ratchet gear mechanism. The carriage release lever above-mentioned is held in a depressed condition so that the position of the carriage is under the control of the feed screw. The particular windings which are energized is dependent upon the size of the letter just typed so that variable spacing is provided.

Referring now to the drawings, and Figures 1 and 2 in particular, one embodiment of the invention comprises a relay apparatus or electromagnet I3 having three separate windings which may be energized either separately or together in various combinations by the key mechanism (3, 4, etc.) of the typewriter I. A switch unit 2 is placed under the key mechanism of typewriter I. In the example shown in Figures 1 and 2, this switch unit includes six switch actuation strings or threads I I which close respective switch contacts (not shown) connected to each thread when the threads are placed under tension. The threads are placed under tension when engaged by projections, such as 8, I0, and I, depending from the arms of the character or spacing keys, such as 3 and 4, of the typewriter. Normally these projections do not engage the threads II. When a particular character key is depressed, however, one or more of threads II are placed under tension, as shown in Figure 3, which closes one or more pairs of switch contacts associated therewith. The closing of a switch couples a suitable voltage source (such as the conventional A. C. line voltage) to one or more of the windings of electromagnet I3. The magnetic force developed in electromagnet I3 attracts a rack wheel actuation lever arm I4 an amount which is dependent on the windings energized. Lever arm IE, which pivots about a pin II, includes an extension I5 made of a magnetic material which is attracted to electromagnet I3, thus pulling down the end of lever arm I4 an amount propor tional to the magnetic force developed by electromagnet I3. Each winding of electromagnet I3 provides a diiferent amount of force when energized. Pivoted to the end of lever arm I 4 is a rack or pawl member 23 which includes an upper offset U-shaped portion including a first toothed portion 24 normally engaging a first gear 3| and a second toothed portion 26 on the other side of gear SI and axially displaced therefrom which is normally adjacent to but disengaged from a second ratchet gear SI. Ratchet gears 3| and 3| are fixedly connected to a spiral lead screw 33 which is normally engaged by a carriage arm 22 riding in the spiral groove of lead screw 33. Screw 33 is rotatably supported in bearings such as 33 connected by brackets to the ends of the stationary frame portion 6!) of the typewriter. Arm 22 extends from carriage 59 which carries the typing paper and moves across the front of the stationary frame portion 60 of the typewriter. As ratchet gears 3| and 3| are rotated by rack or pawl arms 24 and 26 respectively, the lead screw is rotated within bearings 63, etc.; and depending upon the direction of rotation thereof, the carriage arm 22 and carriage 59 may be moved in either the forward or backward direction. The carriage must, of course, be freed from engagement with the carriage rack pawl previously referred to. This is accomplished by keeping the carriage release lever iI depressed. This may be accomplished by means of a screw 40 which is attached to the typewriter by a bracket 42 held in place by a nut 43 (see Figure 1).

The teeth of ratchet gear 3! are adapted to be rotated in a direction by rack arm 24 which will move the carriage 59 to the left as viewed from the front of typewriter I for forward spacing. Rack member 23 is normally held in an upper position by a spring 25 which operates against the force of electromagnet I3. Energization of electromagnet I3 by depression of a character or spacing key pulls down arm I4. As electromagnet I3 is de-energized as the operator lets go of the character key, spring 25 will pull rack arm 2 back into its normal position causing rotation of ratchet gear 3|. Because of the shape of the teeth of the ratchet gear 3! and rack arm 2|, the downward motion of rack 23 will not impart motion to wheel 3| to prevent any back spacing of carriage 59 when the character key is depressed. Only the upward motion of the rack will rotate gear 3I. The amount of retation of ratchet gear 3| is dependent upon the distance the lever arm I4 is pulled downward by electromagnet I3. Rack arm 26 and ratchet gear 3i operate in a similar manner to ratchet 3| and rack arm 24 just described. The direction of the extent of the gear teeth on gear 3I' and rack arm 26 is reversed, however, to provide for back spacing. A lever 3 pivoted about point 28 is actuated by the back space key '5. Thus depression of back space key 5 depresses one end of lever B which causes the other end 29 thereof to be raised. Connected to the end 29 of lever 6 is a transverse rod 62 (shown in dotted lines in Figure 2 since it may not actually be seen from the back of the typewriter) which rides in a slot 21 in rack arm 26. As transverse rod 62 moves upward, it presses against the side of slot 21 thereby pivoting rack 23 about pivot point I9 at the end of lever arm I4. This action pushes rack arm 26 in engagement with ratchet gear 3 I and disengages rack arm 24 from engagement with ratchet gear 3!. Then when a character or spacing key, such as 3 or 4, is depressed, the electromagnet I3 is energized and lever arm I4 is pulled down an amount determined by the key pressed. Ratchet gear 3 I is rotated in a counterclockwise direction as viewed in Figure 1, as the character key is released which de-energizes electromagnet I3. This rotates screw 33 in a direction to move carriage 59 backwards for the back spacing operation. The procedure for back spacing therefore is to hold the back space lever down with the finger of one hand and. then to depress and release the character key which corresponds to the letter previously typed. This returns the carriage to the same position. it was in before the last letter was typed.

In order to prevent the typing of a letter during the back spacing operation, an arm member may be connected to transverse rod 62. A thin plate member is attached to the end of arm member 39 so that as arm member 30 is raised with transverse rod 82, the plate member 35 is raised in front of the type bar (not shown). Plate. member 35 slides behind type bar guide member 3? in the embodiment shown in Figure 1. If the typewriter has a dead key or mimeograph key mechanism which prevents the printing of a character as a key is struck, the back space. key may be adapted to operate the dead key or mimeograph key mechanism.

Since the force of the relay provides the force for moving the carriage, if desired, the forward movement of the carriage may be used to store up energy in a conventional typewrite tapespring apparatus comprising a cylindrical housing 5? and a flexible spring tape 58 which tends to wind itself within housing 5?. The energy used to store up energy in the spring is used for the purpose of returning the carriage to its ini tial position. Thus, as the carriage moves to the right as viewed from the rear of the typewriter as seen in Figure 2, the spring 53 is unwound from housing 58 and is placed under tension much in the same manner as in conventional typewriters except that in such typewriters, the spring tension is used to aid the forward motion rather than the backward motion of the carriage. The position of such a spring apparatus in the more conventional typewriter need only be reversed in position to convert same into the typewriter machine shown in Figure 2.

As shown more clearly in Figure 1, a return key 44 is provided to raise the carriage arm 22 to disengage it from the carriage screw 33. Arm 22 swivels relative to an upper arm member 2| which is directly connected to carriage 59 as by a suitable bracket Zl. The upper arm member 2I- is made to swivel relative to bracket 2| by means of any suitable means such as a nut-and-bolt arrangement 22"--5l passing through holes in the arm member 2! and bracket 21. A similar nut-and-bolt arrangement may be used for the swivel connection between carriage arm member 22 and arm member 2|. Carriage return key 44 is coupled to a lever 45 which pivots about a fixed shaft 4'! so that a downward movement of key 44 produces an upward movement of the end '43 of lever 55. Endportion 48 is connected to carriage arm 22 as by a screw 53 so that the depression of carriage return 44 raises arm 22 from engagement with screw 33 by a swivel motion.

To provide for line spreading, the point about which ratchet wheel actuation lever arm [4 pivots is made variable. For a given attractive force developed by electromagnet I3, the amount of movement of the free end of lever Hi depends upon the point about which lever h! pivots. A bracket I8 is connected to frame portion of typewriter l in any suitable manner and includes a plurality of threaded holes in which a pin I! may be threaded. Lever M has a slot I 6 formed therein with a series of spaced rounded notched portions $6 in the top portion thereof which are placed opposite the threaded holes 6 in bracket H1. The edges of the slots rest on the top of pin 11 when placed adjacent thereto and lever I'4 pivots about pin Ils. If'it is'desired' to spread a given line a small amount to even up the margin, then pin IT is moved to the? next notched position.

Refer now to Figure 3 which discloses the manner in which the relay energizingcontactsare closed in: response to depression of a character or spacing key. A thread it is shown suspended within container 2 shownv in Figure l bymeans of suitable spacers 19, 80, etc. The other threads are similarly supported. When a characterikey 3 is depressed, the projection in presses-downward on thread ll putting it undertensio'n. so that contact 16 of normally openedv contact-pair Hi -I8 is efiectively pulled into engagement with contact. 18 thus completing. an electrical'circult (shown in Figure 5) which energizes -one-of.--the windings. of electromagnet I 3-. Figure 4 shows an alternative but. less preferred manner of closing, the relay energizing contacts: In this embodiment, a separate bar 82 replaces each of the threads; shown-in Figures 1 and 3*. Asin the apparatus shown in Figure 3, each key is provided with projections such as Ill-Which actuate. the particular bar placed beneath it which will actuate the desired winding ofselectromagnet 3; The bars may be held in a raised position by a spring such as 86 at each end thereof which extends upwardly from a. spring housing such as 83 having a hole therein to receive the associated spring. Each bar includes anextension such as 84 carrying an electrical contact on the end thereof such as 81 which is normally held; out of contact with another electrical contact such as 89 by'the associatedyspring. Depres sion of a character or spacing key depresses the appropriate bar by means: of the extension connected to the depressed key bar such as: 9, and the electrical contacts operated by the particular bar are closed thereby energizing electromagnet' l3.

Reference isnow made to Figure 5-which shows the circuit diagram of the energizing-circuit for electromagnet or relayl3. The three windings of electromagnet [-3 are shown as windings 13a, i317, and. I30, respectively. Each winding is coupled to a suitable voltage source through a-connector plug 90 and contactsof various switches now to be described. First, however, it should; be understood that, for the embodiment now described windings [3a, [3b, and Home composed of a different number of turns of wire so that energization of the respective windings produces a different amount of attractive magnetic force. One of the six string H- actuates a difierent one of the six pairs of contacts IS-18, IS -18", 92+, 92'94, 95-418, and 96'--98-' in themanner shown in Figure 3. Thus each character key arm has one or more extensions such as 31, H3, and I0 (see Figure l) overlying the string which itsis to actuate. Where a given key bar does not have such an extension overlying a particular string, then depression of the character key associated with particular bar will not touch the said particular string.

Each-relay or electromagnet winding may be connected to the energizing source by one of two paths. One path (the lower path in Figure 5) is rendered active when the lower case or nonshift letters or symbols are typed while the other path (the-upper path denoted by the primenu-mhers in Figure 5) is rendered active when the shift key 3 (see Figure 1 is depressed. Where a given path is rendered active, the closing of the pair of contacts actuated by the strings II will energize the associated electromagnetic winding but not otherwise (i. e., if it is not active). A ganged group of switches I00, I, I02, I02, I04, and I04 are located in the same paths respectively as relay actuation switches 16-48, I6-'I8', 92-94, 9294', 96-98, and 96'-98'. When the ganged switches are in their lowered position as shown in Figure 5, then the closing of the electromagnetic actuation switches in the lower path will have no effect but will have an effect in the upper path since then the electromagnetic windings have a complete path to the energizing voltage source through the electromagnetic actuation switches and the contacts of the ganged switches. The ganged switches are placed in this lower' position by depression of the conventional shift key 4. (See Figure 1.) A projection 8 is soldered or otherwise connected to arm I of shift key 4 which depresses an arm I2 to which the ganged contacts are connected. The ganged switches are housed in any suitable housin I2 which is located in container 2 which, as previously stated, is placed beneath the keys of the typewriter. Ganged switches are normally held in an upward position by any suitable means such as a spring (not shown). Thus, different spacing may result by depression of a single key through operation of the shift key. Since the upper and lower case letters are usually of dif- 'ferent width, this type of circuit is required for the embodiment shown in Figures 1-5.

If the separate energization of windings I3a, I31), and I3c produces 1, 2, and 4 units of carriage movement, then 3, 5, 6, and '7 units of spacing may be accomplished by simultaneously energizing two or three windings in different combinations. In the embodiment shown in Figures 1-5, a minimum number of 6 pairs of contacts and 6 threads or bars II are needed for 3 to 7 spacing selections because the same contacts are actuated whether the upper or lower case letters of a given character key are selected. Figure 6 discloses a switching system which appreciably simplifies the number of components needed to effect the same results as the embodiment of Figures 1-5 where the typewriter is the type where the type bars are lowered rather than the carriage being raised to effect the typing of upper case or capital letters as in most present day machines.

In the embodiment shown in Figure 6, only three pairs of contacts are needed. Each pair controls the energization of one of the windings I3a, I31), and I3c of electromagnet I3. The movable contacts I6, 92, and 96, respectively, are glued or otherwise connected to resilient arms I I6, H6, and I I6, respectively, which normally hold the attached contacts displaced from the associated contacts I8, 94, and 98. The above elements are connected by any suitable means to a plate member I08 which may be connected to the type bar guide member 31. Type bar guide member 31 is found on most typewriters and includes a pair of guide arms I86 which engage and guide the arms (such as arm I20) to which the type bars (such as IIO) which carry the raised type surfaces are connected. The resilient contact carrying arms II6, H6, and H6 jut out into the general path of the type bars but are placed to avoid. being struck by the side faces of the type except where projections extend from the side thereof. Thus, as shown in Figure 6, an upper group of projections III, and I I2 protrudingfrom the side of a type bar H0 is shown pressing against contact carrying arm members H6 and H6. This closes the pair of contacts I6 and T8, and 92 and 94 which, in turn, causes two of the windings I31; and I3b to be energized. If windings I3a and I3!) individually cause 1 and 2 units respectively of carriage movement, then their combined energization causes a 3 unit movement of the carriage. The upper group of contacts control the energization of electromagnet I3 during the upper case or shift operation of the typewriter. During the nonshift operation, if the switches and type projections are suitably placed, the upper group of projections III and H2 are removed from contact with contact carrying arm members H6 and H6 and the lower group of type bar projections H3, H4, and H5 are moved into engagement with the contact carrying arm members H6, H6, and II6". This simultaneously closes all of the contact pairs so that the maximum spacing results for the upper case letter typed during the shift operation. Of course, the number of projections in the upper and lower groups depends on the sizes respectively of the non-shift and shift (the upper and lower) characters.

The relay or electromagnet I3 shown in Figure 1, as previously stated, operates by providing different levels of magnetic force which accordingly move the lever arm member i4 and the ratchet mechanism associated therewith an amount proportional to this magnetic force.

Figure 7 discloses electromagnetic apparatus I66 of a slightly different character than that shown in Figures 1 and 2. In this apparatus the amount of movement imparted to the ratchet mechanism 23 is not necessarily related to the amount of magnetic force developed by the electromagnetic apparatus but, like Figure l, is re lated to the energized condition of the apparat-us. Thus, electromagnetic apparatus I60 consists of three windings I21, I3 I and I34 which are energized by the depression of the character or spacing keys of a typewriter, either singly or in combination in the same manner as the three windings I3a, [3b, and I3c of electromagnet I3 in Figures 1 and 2. Thus, the same kind of switch devices shown in Figures l-6 may be used with the apparatus shown in Figure '7. The windings 221, I3I, and I35 are wound on separate coil forms I26, I30, and I33, respectively. Each coil unit is made movable with respect to the other to form separate distinct relay units I22, I23, and I224. The three units are mounted one next to the other about a common axis. Each relay unit includes a core movable relative to its associated winding. The cores of relays I23 and I24 move upward when the associated relay is energized and in so doing, bodily moves with it all of the relay units above it. This arrangement in effect provides for as many as seven distinct amounts of movement of lever I5I connected to the core of top relay I22. In the embodiment of Figures 1 and 2, a variation in line voltage used to energize windings I3a, I31), and I30 of electromagnet I3 would vary the amount of movement of the carriage keeping all other conditions constant. This is not so with the apparatus shown in Figure '7.

A more detailed description of the operation and construction of the apparatus of Figure '7 will now be explained.

The top relay unit I22 includes windings i2? wound about a cylindrical core I26 made of any suitable insulating material. The movable core of relay I22 includes a cylindrical member I36 made of any suitable non-magnetic material and a magnetic member I40 cemented or otherpocketor opening in the top portion of a cap member M6, the top portion of which abuts and supports the coil form 225, etc. of relay I22. When current is passed through windings: iii of relay I22, the magnetic core member Hill is attracted upwardly toward the main portion of coil form I22 into the position shown in Figure 8. An annular shoulder I62 is provided on magnetic member MG to limit the upward motion of magnetic member Hi3- as it abuts the bottom of coil form I 26. The amount of upward movemerit-of magnetic member Ice caused by energization of relay I22 is determined by the initial distance betweenthe' top of shoulder I62 and the bottom of the coil form I2 against which it abuts when moved upwardly by the magnetic force of relay I22. Cylindrical core member 536 moves with magnetic member Hill and in so doing, raises an arm member i5 3 connected with it. One end I5I of lever I51; which pivots about a pin I52; is connectedto armmember I59 so that an upward movement of end lei causes a downward movement of the other end I5! of lever I55 The end it of lever i5i is coupled to racl: member 23- in a manner to be described so that energization of relay 22 moves rack member 23 downward. The de-energization of the relay units'cause. rack 23 to move upwardly under the force of spring 25 to move the carriage in the same manner described in connection with the apparatus shown in Figures 1 and 2.

Cap member I 36, it should benoted, does not move at all if only relay H2 is energized. The latter member is connected to the cylindrical core member I3? of the relay I23- .which is just below relay i22. Energization of relay i 2-3 results in anupwardmovementof cylindrical core member i331 ina manner similar to that described in connection with the movement of core member. I33 of relay 522} which raises cap member Mather-cwith. This raises the entire relay I22 with it. A magnetic 'member Mi similar to magnetic member Hit: it fixedly connected tothe bottom of coremember l3? and normally rests in a pocket formedinacap member I 57 associated with relay I25. The distance iromthe annular shoulder i64 of magnetic member Hi to the bottom portion of coil form i38 (when relay i233 isde-energized) is made greater than the equivalent dimensions associated with the components of relay i22. Therefore when-only relay IE3 is energized, the core of relay I23 including elements IEI, I37, andcap-member I48 is raised a greater amount than the core of relay IZZWhen-thelatter relay is alone energized as before described. Since the entire relay IZZ is raised withthe core of relay I23, it-can be seen that energizationof relay I23 alone will raise end IEI of lever I5I a greater amount than if only relay I2-2- wereenergizedthereby providinggreater letter spacing.

If relays I22 and I23" were both energized together, then it shouldbeclear that the amount of upward movement of end IEI of lever I5I will be equal to the sum of the efi'ects of the individual core movements of relays I22 and I23 Relays I24 including cap member I41, cylindrical core member I38; and magnetic member l i2 is similar to the structure and operation ofthe analogous components of relays I22 and I23. Since no relay is located below relay I24, magnetic core member I42 of relay I2 normally (when relay IN is deeenergi zedj rests in the pocket of a stationary base member MS.

It is desired that theen'ergization of relay I-EQ alone should result in a greater amount of movement of lever li'iI' than energization of either relays E22 or [23 alone. distance from the shoulder I65 to the bottom of the coil form- I33: of relay i2 1 (when the latter rclayis tie-energized) is accordingly made greater than the analogous dimensions of relays I22 and I23.

Figure '7- shows the condition of the electromagnetic apparatus 666' when. only relay I24 is energized. I

As long as the voltage applied to the relays I22, I23, and I2 3 sufficiently large to pull the respective magnetic core members I49, MI, and M2- intoabutting relationwith the bottom of the associated coil forms,- the apparatus will operate consistently and accurately.

Needless to say, the amount of movement of raclrmember 23 will be the sum of the individual results of each relay unit.

The embodiment of Figure '7 includes novel line spreading apparatu incorporated into the spacing apparatus there showns 'I'hllfi; thepoint at which the bottom portion ofrack member- 23 connects with lever I51 is made variable with the amount of line; spread desire,d. The closer this connection pointiis to the pivot point I5 2 cf lever I58, the smaller the amount of downward motion results from a given upward motionoi the relay apparatus. Aslot I E lis formed in the end of lever I50 adjacent rack member 23 and a bolt I53 or other suitable adjustable connecting mean passes through slot I54 and a hole in the lower portion I56 of'rack member 23' and is held in place by a nut (not shown)v threaded to the other end of bolt I53. The frictiorl'of the head ofbolt lbltagainst the surface of lever l5! when the nut connected thereto is tightened sufficiently to prevent sliding of' the bolt I53 is slot I54. 7 Rack member 23 is, however; able to rotate a little about bolt I53 as lever I5lis moved about pivot point I521 Lower portion I58 of rack member 23' is pivoted to the upper porti'onther'eof by means of a suitable pivot joint I55 so that the portion of rack member 23 carrying the toothed portions can" freelysli'de' between vertical guides I5. The motion of the toothed portion of rack member 231's thereiore'a linear motion.

A previously stated, many. modifications may be made of the preferred'forms' of "the instantiavention above described without deviating from the spirit and broader scope of the instant invention. I

For example, electronic switches could be substitute'd for the mechanical switch arrangement shown in Figure 6. In such case, each of the projections on the type bar I 10 could be replaced by a small light source" (broadly taken), such as a small circular" area of white paint which reflects more light than the adjacent type bar surface or a small area of radium paint. The mechanical switches could each .be-replaced by a phototube or other suitable light detector which energizes one of the relay windings as the light source moves adjacent the phototube;

Although the back spacing systemshown in Figures I and 2 is especially suitable for an electrically proportional spacing? typewriter as there shown; it could be'adapted Withi advantage to even mechanicallyproportional pacing apparatus where rack member 23 is mechanically rather than electrically moved.

, There are numerous ways to ensure that the lead screw 33 will always be in a position to return to a rotary position such that the carriage arm 22 will engage the lead screw slot when the -carriage is at the left hand margin position. For example, the shaft could be spring biased in such a manner that when arm 22 is raised from the lead screw (the friction between the arm 22 and the screw could be made sufficiently to prevent rotation of the screw by the biasing spring), the said screw is free to rotate a small amount under the force of the spring to a fixed predetermined position. Since such a spring-biased shaft arrangement is obviously old in the art (for example, such an arrangement is found in the cylinders supporting the common draw shade), it is felt unnecessary to describe the details of such a spring biasing arrangement.

The instant invention thus provides a new and improved proportional spacing device which is relatively simple and inexpensive to use and which is especially adaptable for use in converting fixed spacing typewriters to variable spacing typewriters.

We claim:

1. In combination with the carriage and key mechanism of a typewriter, a gear means coupled to said carriage to move same a distance proportional to the movement thereof, a rack member having first and second toothed portions extending on opposite sides of said gear means for an engagement with the teeth thereof to move said gear means, said toothed portions of said rack member being spaced to allow engagement of only one toothed portion at a time with said gear means, said first toothed portion normally in engagement with said gear means during forward movement of said carriage, means actuated by the back space key mechanism of said typewriter to move said first toothed portion of said rack member out of engagement with said gear means and to simultaneously move said second toothed portion thereof into engagement with said gear means, rack actuation means coupled between the character key mechanism of said typewriter and said rack member to move the toothed portions thereof an amount proportional to the size of the letter printed by the particular key struck, and letter blanking means actuated by the back space key for preventing the printing of any letters as a character key mechanism is operated during a back spacing operation.

2. The combination of claim 1 characterized further by said gear means coupled to said carriage through a fixed feed screw rotated directly thereby and a feed screw thread engaging arm extending from the carriage to abut the sides of the feed screw threads and be moved thereby as said feed screw is rotated.

. prevent same from striking the typewriter paper.

5. The combination of claim 1 characterized further by said rack actuation means comprising an electromagnet for imparting rotation to said rack member, a source of electrical energy for said electromagnet, and electric contact means coupled between said source of electrical energy and electromagnet and actuated by the character key mechanism of said typewriter to energize said magnet to a degree proportional to the desired spacing, said rack member being in cooperative relation with said electromagnet so as to be movable an amount proportional to the degree of energization of said electromagnet.

6. The combination of claim 5 characterized further by said electrical contacts being mounted on an insulating support member mounted adjacent the type bar guide member, said contacts being mounted for actuation by projections on the side faces of the type bar.

7. The combination of claim 1 characterized further by said gear means comprising first and second ratchet wheels mounted on a common shaft and having teeth of opposite type for rotation in opposite directions when engaged by the first and second toothed portions of said rack member, said first toothed portion of said rack member mounted adjacent one of said ratchet wheels and the said second toothed portion mounted adjacent said other ratchet wheel.

8. In combination with the carriage and character key mechanism of a typewriter, proportional spacing apparatus comprising an electromagnetic means for imparting motion to said carriage, ratchet mechanism including a rotatable ratchet wheel and a pawl means spring biased for rotating said ratchet wheel in only a first direction, said pawl means being movable by said electromagnetic means to a degree proportional to the degree of energization thereof, electrical contacts mounted for actuation by the character key mechanism of said typewriter for selecting the level of energization of said electromagnetic means, and means converting the rotary motion of said ratchet wheel to longitudinal motion of said carriage.

9. In combination with the carriage and character key mechanism of a typewriter, proportional spacing apparatus comprising electromagnetic means for developing a selectively variable attractive force, first means including a portion made of a magnetic material mounted for movement in an amount determined by the magnitude of magnetic force of said electromagnetic means, second means for coupling the motion of said first means to said carriage, and third means actuated by the character key mechanism of said typewriter for causing said electromagnetic means to develop a magnetic force proportional to the width of the character struck.

10. Apparatus for converting a fixed spacing typewriter having a carriage, character keys, and a carriage release key to a proportional spacing typewriter comprising a box beneath said typewriter containing a plurality of oblong switch actuation members extending transversely of and beneath the character key arms of said fixed spacing typewriter and respective electrical contacts coupled to said switch actuation members for actuation thereby, a spiral threaded screw rotatably mounted to the stationary frame of said fixed spacing typewriter; an arm extending from the carriage of said typewriter and engaging the sides of the threads of said screw for movement in response to rotation of said spiral screw; electromagnetic means adapted to be energized to a plurality of diiferent conditions for moving said carriage varying amounts; means for coupling said electrical contacts between said electromagnetic means and a source of energizing voltage; the condition of said electromagnetic means determined by the selection of the contacts to be actuated by said switch actuation members; said character key arms including portions which abut the particular switch actuation members upon depression of said key arms to produce the desired condition of said electromagnetic means; lever means including a toothed portion on the end thereof mounted for movement by said electromagnetic means an amount variable with the energization condition of said electromagnetic means; and gear means coupled to said spiral screw for rotating same and mounted for engagement with and rotation by the toothed portion of said lever means in an amount varying with the amount of movement of said lever means.

11. The combination of claim 8 characterized further by said electrical contacts mounted on an insulating supporting member adjacent the said carriage of the typewriter, said electrical contacts comprising a plurality of normally opened pairs of contacts having projecting portions extending into the path of movement of the type bars of the typewriter, and projections on the side of the type bars of said typewriter for abutting the projecting portions of the contact pairs producing the desired letter spacing.

12. In combination with the carriage, type bars and type bar guide member of a typewriter, proportional spacing apparatus comprising a plurality of space selecting elements for moving said carriage different amounts after the typing of a letter, a plurality of electric contact pairs for connecting a source of energizing voltage to said space selecting elements mounted adjacent said type guide member, said contact pairs each having a projecting portion extending into the general path of movement of the said type bars for actuating the associated contact pair when engaged by a projection on said type bars, and projections on said type bars positioned for engagement with the appropriate projecting portion of said contact pairs to select the proper space selecting element for energization depending on the width of the letter just typed.

13. In combination with the carriage and type bars of a typewriter having two characters printable by the depression of a single character key by means of a shift key mechanism which varies the vertcial position of the type bars, proportional spacing apparatus comprising a plurality of space selecting elements for moving said carriage different amounts after the typing of a letter, a plurality of electric contact pairs for connecting a source of energizing voltage to said space selecting elements, said contact pairs each having a projecting portion extending into the general path of movement of the said type bars for actuating the associated contact pair when engaged by a projection on said type bar, and two vertically spaced groups of projections on said type bars for engagement with the appropriate projecting portions of said contact pairs respectively only during shift and non-shift operation of the type- 14 writer to select the proper space selecting elements for energization depending on the width of the letter just typed.

14. In combination with the carriage and character key mechanism of a typewriter, proportional spacing apparatus comprising a plurality of axially displaced, contiguous coaxial electrical relay coils mounted for movement along their common axis, a separate core in each relay axially movable a fixed amount in the same direction relative to its associated coil as same is energized, respective means assiciated with the coils of the said relay coils for bodily moving the next successive relay coil and its core simultaneously with movement thereof, linkage means coupled to the core of the last successive relay for moving said carriage an amount proportional to the total displacement thereof, respective electrical contacts connected to said respective relay coils for connecting a source of voltage thereto to energize same, and means responsive to depression of said character key mechanism to actuate the particular electrical contacts which will cause a movement of said carriage proportional to the width of the letter just typed.

15. The combination of claim 14 characterized further by said linkage means including a pivoted lever coupled to the core of the said last relay, the distance of the free end thereof from the point of pivot being gradually variable whereby variable line spreading is provided.

16. In combination with the carriage and key mechanism of a typewriter, variable spacing apparatus comprising electromagnetic means for developing a force to move said carriage, a plurality of pairs of electrical contacts for coupling a source of energizing voltage to said electromagnetic means to vary the energization thereof, as determined by the particular pairs of contacts which are closed, means actuated by the character keys of said typewriter for closing the particular electrical contact pairs which will develop a level of energization in said electromagnetic means proportional to the width of the character struck, and means including a lever pivoted intermediate its ends with one end coupled to said carriage, said lever being movable an amount proportional to the degree of energization of said electromagnetic means to move said carriage a distance proportional to the width of a letter just typed, the distance between the end of said lever coupled to said carriage and the point of pivot of the lever being variable whereby line spreading is provided.

ERIK FREY. RUSSELL E. HATTIS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,349,470 Jackson Apr. 13, 1948 2,487,373 Reppert Nov. 8, 1949

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